Ambushes are a type of battle in the Total War series. They occur when armies march into the path of an army that was previously hidden from their view.
Ambushes are often beneficial, but there are instances where ambushing an army may not be a good idea. Ambushing a numerically superior foe can backfire if the ambushing army is spread thin trying to surround their enemy.
Empire: Total War[]
In Empire: Total War, ambushes allow players to attack enemies from a wide deployment zone surrounding the enemy army's deployment zone (as opposed to most battles where players are only able to deploy in zones opposite each other). This gives the army being ambushed a severe disadvantage as the attacking army can begin the battle attacking from practically all sides. The defending army always has its army starting the battle in an unwieldy column formation and must scramble to form lines to even the odds. It skips the deployment phase altogether and there are no opportunities to place deployment options such as Chevaux de Frise or Earthworks.
Only armies led by generals with certain traits may conduct ambushes. Armies that can ambush are depicted on the world map as taking a crouching stance. Enemy armies that are ready to ambush are hidden from the player on the world map, and are only revealed if they move or if they spring their ambush.
Napoleon: Total War[]
In Napoleon: Total War, any army may ambush as long as they are hiding in forests that are labeled as being able to spring an ambush from. Other than this, the mechanics are identical to Empire: Total War.
The spy's underground networking ability does not reveal enemy armies lying in wait of ambush. However, a spy that is attached to an enemy army always keeps the enemy army visible, allowing the player to avoid potential ambushes easily.